The art recognizes the great difficulties commonly associated with extinguishing coal fueled fires. This is especially so in fires burning in coal mines. Prior to the invention, it was, as a practical matter, almost impossible to extinguish a coal fueled fire in a coal mine once the fire reached significant proportions. Attempts to extinguish such fires with water, or water and foam, are ineffective. The water has insufficient penetration and latent heat evaporazation to effect extinguishment. Foam has no penetrating ability to extinguish deep seated coal fires, it will roll off very hot coal fires, and it can separate into constituents with the acid content of the foam actually fueling the fire, and being burned along with the coal.
In U.S. Pat. No. 4,248,733 a fire extinguishing medium is provided which can be effective for extinguishing coal fires, even though there is no specific disclosure in that patent for extinguishing coal fires. If the composition in said patent is applied to a coal fire, it can be effective in ultimately extinguishing the fire, however it must be applied at a relatively high metering rate with respect to water (e.g. at about a 10-20% dilution rate to water) in order to be effective, has a toxicity problem in that components thereof (particularly the urine and alfalfa) generate gases which are toxic to humans, and does not have a penetration rate that is as high as desired.
According to the present invention a coal fire fighting formulation is provided, as well as a method of fighting coal fires, which overcomes the drawbacks associated with the prior art discussed above. According to the invention it is possible to extinguish coal fueled fires even when there is pyrolysis (the phenomena of the coal having a tendency to self-generate and produce some of its own oxygen to maintain a sustained burn, in limited oxygen atmospheres). This can be accomplished with a relatively low metering rate of the liquid formulation to water, and with no toxicity; that is gases generated are not toxic to humans. Further, according to the present invention the formulation deeply penetrates the coal, resulting in quicker and more effective extinguishment, quicker and more effective absorption of fire gases, and prevention of reignition. For example, in the practice of the present invention, as compared to the application of the formulation of the U.S. Pat. No. 4,248,733 to a coal burning fire, the invention is as effective when metered at about a 6% dilution rate to water as the liquid composition of the patent at a dilution rate of about 10 to 12% to water. The invention also penetrates more quickly, and has zero toxicity, whereas the urine and alfalfa components of the formulation of the patent result in the generation of gases which are toxic to humans. In fact, the formulation according to the invention has been approved by the Bureau of Mines for application to coal burning fires, including in coal mines.
According to the present invention it is also possible to use the formulation at a dilution rate of about 0.25-0.5% to water to absorb methane, and other gases generated by a coal burning fire, merely by spraying the composition in water into the air containing the gases. Also according to the invention it is possible to retard spontaneous ignition of coal by spraying the liquid composition at a dilution rate of about 0.5-1.5% to water, directly onto the coal surface, the retardation of spontaneous ignition lasting almost indefinitely as long as there are no significant increases in temperature or pressure.
The liquid formulation according to the present invention preferably consists essentially of a linear alkylbenzolyate sulfonate, non-ionic detergent and lauric superamide detergent mixture comprising about 50% by volume of the formulation, vitamin B-6 in an amount of about 0.5-3% by weight of the detergent mixture, bicarbonate of soda in the amount of about 3-18% by weight of the detergent mixture, non-toxic coloring and perfuming agents if desired, and water comprising about 37-47% by volume of the total formulation. The detergent mixture itself is most effective when it comprises, by volume: about 10-40% linear alkybenzene sulfonate about 2-12% isooctylphenyl polyethoxyethanol; about 0-5% polyoxyethylene sorbitan monooleate; about 2-10% lauric diethanolamides; about 0-2% monoethanolamide superamides; and about 31-86% water. It is highly desirable to add a non-toxic red dye, such as red vegetable color, to the formulation, in an amount of about 0.25-0.75% by weight of the detergent mixture. The red dye is effective to cause a red colored light reflection off of a surface to which it has been applied when the fire has been extinguished. This red colored light reflection serves as an indication to the firefighters that the fire at that particular surface has been extinguished, and it is safe to proceed further into the mine tunnel or shaft to fight the fire therein.